Traditional Internet Protocol (IP) communication allows a source device to send packets to a single network-connected destination device (unicast transmission) or to all network-connected destination devices (broadcast transmission). A third technique, referred to as multicast transmission or multicasting, has evolved to support increased demands for various audio and video applications (e.g., online conferences, video on demand, etc.) that involve high data rate transmission to multiple (but not all) destination devices.
Multicasting is a form of communication that allows a source device to send an IP packet to a network for distribution to multiple destination devices. The network usually includes at least one multicast-enabled networking device (e.g., router or other switching device) configured to replicate the packet and forward the replicated packets to the multiple destination devices. Multicast-enabled networking devices typically include a centralized controller to replicate the received packets, and one or more output interfaces (ports) to forward the replicated packets to the destination devices over various data links.